Image analysis device and X-ray diagnostic apparatus

ABSTRACT

According to one embodiment, an image analysis device includes a parameter value acquisition unit, a color allocation unit and a time phase image generation unit. The parameter value acquisition unit acquires a parameter value per pixel, on the basis of time variation of pixel values per pixel corresponding to the same region of an object in image data of a plurality of sequential DSA images. The color allocation unit generates a color map in which a (chromatic) color in accordance with the parameter value is allocated per pixel corresponding to the same region of the object. The time phase image generation unit generates color image data of time phase images respectively corresponding to a plurality of time phases, by reflecting information in accordance with pixel values of the DSA images to each pixel of the color map.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a continuation of U.S. application Ser. No.14/533,622, filed Nov. 5, 2014, which is based upon and claims thebenefit of priority from Japanese Patent Application No. 2013-255701,filed on Dec. 11, 2013;

The entire contents of which are incorporated herein by reference.

BACKGROUND OF THE INVENTION 1. Field of the Invention

Embodiments described herein relate generally to an image analysisdevice and X-ray diagnostic apparatus.

2. Description of the Related Art

As endovascular therapy, a vasodilation operation in which blood vesselsare dilated from inside by using a catheter or the like and a vascularembolus operation which aims to necrotize a tumor by embolizing theblood vessels providing nutrition to the tumor are known. In order toconfirm the effect of such vascular therapy, DSA (Digital SubtractionAngiography) images are used (for example, see Japanese PatentApplication Laid-open (KOKAI) Publication No. 2006-87631).

The DSA images are obtained by, for example, sequentially imaging thesame region of a patient before and after administration of a contrastagent with the use of an X-ray diagnostic apparatus. More specifically,a plurality of subtraction images obtained by subtracting a mask imagebefore administration of the contrast agent from the image of each timephase after administration of the contrast agent so as to respectivelycorrespond to the time phases are defined as the DSA images.

In conventional technology, the sequential DSA images are generatedbefore and after an operation respectively, and a reader confirms theeffect of the operation by visually comparing these DSA images. Theconfirmation of the effect of the operation means judgment(identification) of a bloodstream improving region in the case of thevasodilation operation and means judgment of a bloodstream occludedregion in the case of the vascular embolus operation, for example.

If comparison between moving image display of the DSA images before theoperation and moving image display of the DSA images after the operationdoes not clearly indicate degree of bloodstream improvement or aposition of a bloodstream occluded region, a reader selects an arbitraryone image out of the DSA images before the operation, selects anarbitrary one image out of the DSA images after the operation, and thencompares these selected two images as still pictures. It is notnecessarily easy to identify a slight difference in bloodstream betweenbefore and after the operation by visually comparing the DSA imagesbefore and after the operation.

Therefore, a novel technology to enable visual confirmation of a regionwith changed bloodstream amount based on DSA images before an operationor based on DSA images after start of an operation more easily thanconventional technology has been desired.

For example, a novel technology to enable visual confirmation of theregion with changed bloodstream amount after an operation such as abloodstream improving region after the vasodilation operation and abloodstream occluded region after the vascular embolus operation, on thebasis of the DSA images before and after an operation, more easily thanconventional technology has been desired.

BRIEF DESCRIPTION OF THE DRAWINGS

In the accompanying drawings:

FIG. 1 is a block diagram showing an example of the structure of theX-ray diagnostic apparatus of the present embodiment;

FIG. 2 is a schematic diagram showing a calculating method of timevariation of concentration of the contrast medium, as an example ofacquiring parameter values in the generation process of the parametricimages;

FIG. 3 is a schematic diagram showing an example of generation methodsof the parametric images whose parameter is TTP;

FIG. 4 is a schematic diagram showing the first example of the method ofgenerating the parametric time phase images conducted by the time phaseimage generation unit, in a step-by-step manner;

FIG. 5 is a schematic diagram showing the second example of the methodof generating the parametric time phase images conducted by the timephase image generation unit, in a step-by-step manner;

FIG. 6 is a schematic diagram showing the judging method of abloodstream improving region after the vasodilation operation or thelike conducted by the specifying processing unit, in a stepwise fashion;

FIG. 7 is a schematic diagram showing an example of distinguishablydisplaying the bloodstream improving region by surrounding it with aframe, in moving picture display of the parametric time phase images;

FIG. 8 is a schematic diagram showing an example of distinguishablydisplaying the bloodstream improving region by blinking it, in movingpicture display of the parametric time phase images;

FIG. 9 is a schematic diagram showing an example of a highlighted bloodvessel wall extracted by the specifying processing unit, in movingpicture display of the parametric time phase images;

FIG. 10 is a schematic diagram showing an example of displaying only thebloodstream improving region by using the DSA images as a movinggray-scale picture and displaying the rest of the regions in color byusing the parametric time phase images, in moving picture display of theparametric time phase images;

FIG. 11 is a flow chart showing an example of the operation of the X-raydiagnostic apparatus of the present embodiment, when imaging withadministration of the contrast agent before and after the vasodilationoperation and display of the bloodstream improving region are performed;and

FIG. 12 is a flow chart showing an example of the operation of the X-raydiagnostic apparatus of the present embodiment, when imaging withadministration of the contrast agent before and after the vascularembolus operation and display of the bloodstream occluded region areperformed.

DETAILED DESCRIPTION

Hereinafter, examples of aspects which embodiments of the presentinvention can take will be explained per aspect.

(1) According to one embodiment, an image analysis device includes a DSAimage acquisition unit, a parameter value acquisition unit, a colorallocation unit and a time phase image generation unit.

The DSA image acquisition unit acquires a plurality of sequential(time-series) DSA images of the same object.

The parameter value acquisition unit acquires a parameter value perpixel, on the basis of time variation of pixel values per pixelcorresponding to the same region of the object in the image data of theplurality of sequential DSA images.

The color allocation unit generates a color map in which a color inaccordance with the parameter value is allocated per pixel correspondingto the same region of the object.

The time phase image generation unit generates color image data of timephase images respectively corresponding to a plurality of time phases,by reflecting information in accordance with pixel values of the DSAimages to each pixel of the color map.

(2) In another embodiment, an X-ray diagnostic apparatus includes anX-ray imaging unit and the image analysis device of the above (1).

The X-ray imaging unit generates projection data of X-ray images bydetecting X-rays passing through an object before and afteradministration of a contrast agent, and generates image data of aplurality of sequential DSA images of the object on the basis of eachsubtraction between an X-ray image before administration of the contrastagent and each of sequential X-ray images after administration of thecontrast agent.

The image analysis device acquires a parameter value per pixel, on thebasis of time variation of pixel values per pixel corresponding to thesame region of the object in the image data of the sequential DSAimages, generates a color map in which a color in accordance with theparameter value is allocated per pixel, and generates color image dataof time phase images respectively corresponding to a plurality of timephases, by reflecting information in accordance with pixel values of theDSA images to each pixel of the color map.

In the following, embodiments of the present invention will be describedwith reference to the accompanying drawings. Note that the samereference numbers are given for identical components in each figure, andoverlapping explanation is abbreviated.

<Structure of the Present Embodiment>

FIG. 1 is a block diagram showing an example of the structure of theX-ray diagnostic apparatus 10 of the present embodiment. As shown inFIG. 1, the X-ray diagnostic apparatus 10 includes an input device 22,an image analysis device 24, a system control unit 26, a projection datastorage unit 28, a projection data generation unit 30, an X-ray detector34, a C-arm 36, a table 38, a diaphragm device 40, an X-ray tube 42, ahigh-voltage generator 44, a diaphragm control structure 46, a tablemoving structure 48, a C-arm control structure 50, and a detector movingstructure 54.

Because the main characteristics of the X-ray diagnostic apparatus 10are the functions of the image analysis device 24, the functions of theother components are simply explained as follows and then the functionsof the image analysis device 24 will be explained in detail.

An object P is loaded on the table 38.

The C-arm 36 is an arm holding the X-ray tube 42, the diaphragm device40 and the X-ray detector 34. By this C-arm 36, the X-ray tube 42 andthe diaphragm device 40 are disposed to face the X-ray detector 34 withthe object P interposed therebetween.

The high-voltage generator 44 generates high voltage and supplies thegenerated high voltage to the X-ray tube 42.

The X-ray tube 42 generates X-rays by using the high voltage suppliedfrom the high-voltage generator 44.

The diaphragm device 40 narrows down the generated X-rays so as toselectively irradiate the imaging region of the object P, by sliding aplurality of diaphragm blades, for example.

The diaphragm control structure 46 controls irradiation range of X-raysby adjusting degree of opening of diaphragm blades of the diaphragmdevice 40.

The X-ray detector 34 converts the X-rays passing through the object Pby using many X-ray detection elements arrayed in a matrix into electricsignals as an example, accumulates the electric signals, and inputs theaccumulated electric signals into the projection data generation unit30.

The projection data generation unit 30 generates projection data byusing the electric signals inputted from the X-ray detector 34, andmakes the projection data storage unit 28 store the generated projectiondata. The projection data are, for example, image data of an X-ray imagein which each pixel has one pixel value, and each pixel value of theprojection data reflects X-ray transmissivity of the imaging region ofthe object.

As an example here, it is assumed that the projection data generationunit 30 also generates image data of the DSA images on the basis of theprojection data and makes the projection data storage unit 28 store theimage data of the DSA images.

However, as an alternative structure, a DSA image acquisition unit 24 aof the image analysis device 24 may acquire the projection data of X-rayimages and generate the image data of the DSA images on the basis of theacquired projection data.

The input device 22 includes a keyboard, a mouse, buttons and so on fora user to input various commands such as imaging conditions and imageprocessing conditions. The input device 22 transfers the inputtedcontents to the system control unit 26.

The system control unit 26 controls the entirety of the X-ray diagnosticapparatus 10 as to setting imaging conditions, imaging operation anddisplay processing.

Next, each component of the image analysis device 24 will be explained.

The image analysis device 24 includes a system bus SB, the DSA imageacquisition unit 24 a, a parameter value acquisition unit 24 b, a colorallocation unit 24 c, a time phase image generation unit 24 d, aspecifying processing unit 24 e and a display unit 24 f.

The system bus SB is a communication wiring that electricallyinterconnects the respective components of the image analysis device 24.

The DSA image acquisition unit 24 a acquires, from the projection datastorage unit 28, the image data of the plurality of sequential DSAimages obtained by performing imaging on the same object before andafter administration of the contrast agent.

The parameter value acquisition unit 24 b acquires parameter values perpixel for parametric imaging, on the basis of time variation of pixelvalues per pixel corresponding to the same region of the object in theimage data of each DSA image (see the later-described FIG. 2).

The above parametric imaging is, for example, processing of forming acolor image or gray-scale image from a single parameter or a pluralityof parameters. In a broad sense, the parametric imaging includes theprojection data of X-ray images generated by the projection datageneration unit 30. This is because the pixel value of each pixel in thecase of the projection data of X-ray images indicates a value of X-raytransmissivity as a parameter.

In a narrow sense, the parametric imaging means processing ofcalculating parameter values except X-ray transmissivity per pixel onthe basis of the projection data of X-ray images so as to form a colorimage. In the present embodiment, the parametric imaging in the narrowsense will be explained from FIG. 2. In addition, in the followingexplanation, images generated by the parametric imaging in the narrowsense are defined as parametric images.

The color allocation unit 24 c generates the image data of parametricimages (i.e. the color map) in such a manner that (a) a color inaccordance with the parameter value is allocated per pixel correspondingto the same region of the object P and (b) chromatic colors areallocated to a plurality of pixels.

The image data of parametric images are, for example, image data inwhich each pixel has three pixel values respectively corresponding tothe three primary colors of red, green and blue. As an example here, itis assumed that image data of one parametric image is generated for oneset of a series of sequential DSA images.

The time phase image generation unit 24 d generates color image data ofa plurality of parametric time phase images respectively correspondingto a plurality of time phases, by performing color conversion per pixelof one parametric image. As to details of the parametric time phaseimages, it will be explained later. In addition, the above “a pluralityof time phases” means, for example, the time phases of the respectiveDSA images that are production source of the parametric image.

The specifying processing unit 24 e specifies a region with changedbloodstream amount, on the basis of subtraction between each parametricimage before operation and each parametric image after the operation.The above “region with changed bloodstream amount” means a bloodstreamimproving region in the case of the vasodilation operation and means abloodstream occluded region in the case of the vascular embolusoperation, for example.

The display unit (monitor) 24 f displays GUI (Graphical User Interface)for receiving commands from a user via the input device 22 and X-rayimages. In addition, as one of the main characteristics of the presentembodiment, the display unit 24 f performs moving picture display ofeach color image data of the plurality of images respectivelycorresponding to a plurality of time phase during which the above regionwith changed bloodstream amount can be distinguished.

Hereinafter, the functions of the image analysis device 24 includinggeneration of the parametric images and extraction of the region withchanged bloodstream amount will be explained in detail with reference toFIG. 2 to FIG. 6.

FIG. 2 is a schematic diagram showing a calculating method of timevariation of concentration of the contrast medium, as an example ofacquiring parameter values in the generation process of the parametricimages. The upper part of FIG. 2 indicates the DSA images of therespective time phases, and the lower part of FIG. 2 indicates anexample of time variation of concentration of the contrast agentfocusing on one pixel.

For example, consider a case where the projection data of six X-rayimages of the same imaging region of the same object P are generated bythe projection data generation unit 30 in the order of time t=0 beforeadministration of the contrast agent and time t=1, 2, 3, 4, 5 afteradministration of the contrast agent, under imaging operation of theX-ray diagnostic apparatus 10.

In this case, image data of five DSA images (subtraction images)respectively corresponding to t=1, 2, 3, 4, 5 are obtained bysubtracting the X-ray image at t=0 (i.e. the mask image) from each X-rayimage after administration of the contrast agent (see the upper part ofFIG. 2). Note that, in the upper part of FIG. 2, t=1 is described astime phase 1, and t=2 is described as time phase 2 (the same applieshereinafter).

Here, the parameter value acquisition unit 24 b calculates timevariation of concentration of the contrast agent per pixel, bycalculating time phase variation (from t=1 to t=5) of pixel values perpixel of the same position through the five DSA images.

The lower part of FIG. 2 indicates an example of time variation of theconcentration of the contrast agent focusing on the bottom left pixel ofeach DSA image (in this case, the pixel number of each DSA image is fivelines times five columns). In the lower part of FIG. 2, the verticalaxis indicates concentration of the contrast agent (intensity ofcontrast agent), and the horizontal axis indicates time phase (elapsedtime t).

More specifically, because the X-ray absorption rate of the contrastagent is higher than that of human tissues, exposure dose of an X-raydetection element corresponding to the position of the object P, wherethe concentration of the contrast agent is high, becomes lower, and thecontrast agent is darkly projected in an X-ray image more than itssurrounding areas. Because each pixel value of each DSA image is adifference value from the pixel value of the same position of the maskimage (before administration of the contrast agent), if the pixel of thesame position is focused on and appropriate processing such as signinversion is performed on time phase variation of the pixel value ofthis pixel, the result becomes equivalent to time variation of theconcentration of the contrast agent.

The parameter value acquisition unit 24 b acquires, for example, atleast one of the following three parameters for each pixel, on the basisof the time variation of the concentration of the contrast agentcalculated in the above manner.

Firstly, it is TTP (Time To Peak), and TTP indicates at which time phasethe concentration of the contrast agent reaches the peak. In the exampleof the above bottom left pixel, because the concentration of thecontrast agent reaches the peak at time phase 3, 3 is given as aparameter value.

Secondly, it is PH (Peak Height), and PH indicates the peak value of theconcentration of the contrast agent. In the example of the above bottomleft pixel, it is the value of the vertical axis at time phase 3. Notethat, the range of the values of the vertical axis can be arbitrarilyset in accordance with dynamic range, for example.

Thirdly, it is AUC (Area Under Curve), and AUC indicates a timeintegration value of the concentration of the contrast agent from thefirst time phase to the final time phase of the DSA images. In theexample of the above bottom left pixel, AUC corresponds to squaremeasure of the diagonally right down shadow region in the lower part ofFIG. 2.

The parameter value acquisition unit 24 b calculates at least one of theabove three parameters for all of the other pixels, by similarlycalculating the time variation of the concentration of the contrastagent.

FIG. 3 is a schematic diagram showing an example of the generationmethods of the parametric images whose parameter is TTP. The upper partof FIG. 3 shows an example of TTP values calculated per pixel of thesame position through a plurality of the DSA images, assuming that thepixel number is 5×5, for example.

The middle part of FIG. 3 shows an example of a color table for TTPstored in the color allocation unit 24 c. As an example in FIG. 3, redis allocated to pixels whose TTP values are 1, yellow is allocated topixels whose TTP values are 2, green is allocated to pixels whose TTPvalues are 3, blue is allocated to pixels whose TTP values are 4, andpurple is allocated to pixels whose TTP values are 5.

Although allocation method of color is arbitrary, it is preferable toallocate colors so as to include chromatic colors. This is because it isdifficult to distinguish a blood vessel part from its surrounding areasin gray-scale display.

Although three primary colors of red, green and blue are used in theabove example of color allocation, this is only an example. For example,color allocation may be performed so that one of the three pixel valuesof red, green and blue of each pixel becomes always zero. Alternatively,color allocation may be performed so that two of the three pixel valuesof red, green and blue of each pixel become always zero.

Although the color table is indicated by a gray-scale horizontal bar inFIG. 3 for reasons of expediency, actually color tables may be stored ascolor bars of chromatic colors.

Alternatively, the color allocation unit 24 c may store color tables astable data in which a set of the respective three values of the threeprimary colors of red, green and blue is indicated in predetermined bitnumber for each TTP value. For example, in the case of 8 bits, (255, 0,0) is allocated as each value of red, green and blue for TTP=1.

The lower part of FIG. 3 indicates the color of each pixel defined bythe color table in the middle part of FIG. 3 and the TTP value of eachpixel in the upper part of FIG. 3. That is, the parametric image of TTPis an image in which the color of each pixel is displayed so as toaccord with the color shown in the lower part of FIG. 3.

Note that, the color allocation unit 24 c also stores color tables forother parameters such as the color table for AUC and the color table forPH. Although the parametric image is generated by using TTP as aparameter in the above example, the parametric image may be generated byusing the aforementioned AUC or PH as a parameter. In addition, thetypes of parameters are not limited to TTP, AUC or PH. For example, anaverage value of rising inclination up to the peak in the concentrationof the contrast agent may be alternatively used as a parameter.

As just described in FIG. 2 and FIG. 3, one parametric image isgenerated for a plurality of sequential DSA images by the parametervalue acquisition unit 24 b and the color allocation unit 24 c.

Next, as one of the characteristics of the present embodiment, the timephase image generation unit 24 d generates color image data of aplurality of time phase images respectively corresponding to theplurality of sequential DSA images, from one parametric image. In thefollowing explanation, each of the sequential color images generatedfrom one parametric image is referred to as “a parametric time phaseimage”.

FIG. 4 is a schematic diagram showing the first example of the methodsof generating the parametric time phase images conducted by the timephase image generation unit 24 d in a step-by-step manner.

The uppermost part of FIG. 4 indicates five sequential DSA images shownin FIG. 2. In the example of the uppermost part of FIG. 4, thesequential pixel values of the bottom left pixel through the respectiveDSA images are 0, 179, 255, 127, 26 from time phase 1 to time phase 5 inorder, and the maximum value of them is 255 at time phase 3.

If the above sequential pixel values are normalized on the basis of themaximum pixel value, they become 0%, 75%, 100%, 50%, 10% from time phase1 to time phase 5 in order (see the second uppermost part of FIG. 4).

Here, in the aforementioned example, the color allocated to the bottomleft pixel in the parametric image whose parameter is TTP is green (seethe third uppermost part of FIG. 4).

As an example here, the time phase image generation unit 24 d performscolor conversion on the color of the bottom left pixel of the parametricimage, so that the color conversion depends on each pixel value of thepixel of the same position (i.e. bottom left pixel) in the sequentialDSA images.

That is, a known color conversion processing is performed on the bottomleft pixel of the parametric image, in such a manner that chroma becomes0%, which is the normalized pixel value of the bottom left pixel of theDSA image at time phase 1. Thereby, the color after this colorconversion processing becomes the color of the bottom left pixel of theparametric time phase image at time phase 1.

Similarly, the color conversion processing is performed on the bottomleft pixel of the parametric image in such a manner that chroma becomes75% (which is the normalized pixel value of the bottom left pixel of theDSA image at time phase 2), and the color subjected to this colorconversion processing becomes the color of the bottom left pixel of theparametric time phase image at time phase 2.

Similarly, the color conversion processing is performed on the bottomleft pixel of the parametric image in such a manner that chroma becomes100% (which is the normalized pixel value of the bottom left pixel ofthe DSA image at time phase 3), and the color subjected to this colorconversion processing becomes the color of the bottom left pixel of theparametric time phase image at time phase 3.

Similarly, the color conversion processing is performed on the bottomleft pixel of the parametric image in such a manner that chroma becomes50% (which is the normalized pixel value of the bottom left pixel of theDSA image at time phase 4), and the color subjected to this colorconversion processing becomes the color of the bottom left pixel of theparametric time phase image at time phase 4.

Similarly, the color conversion processing is performed on the bottomleft pixel of the parametric image in such a manner that chroma becomes10% (which is the normalized pixel value of the bottom left pixel of theDSA image at time phase 5), and the color subjected to this colorconversion processing becomes the color of the bottom left pixel of theparametric time phase image at time phase 5.

Note that, because the color of the bottom left pixel of the parametricimage is indicated by red=0, green=255 and blue=0 under 8-bit notationof the three primary colors and the chroma of this pixel is originally100% in the above example, the color of the bottom left pixel of theparametric time phase image at time phase 3 is the same as the color ofthe bottom left pixel of the parametric image.

Thereby, each color of the bottom left pixel of the respectiveparametric time phase images from time phase 1 to time phase 5 aredetermined. As to other pixels, the respective colors of every pixel ofthe parametric time phase images from time phase 1 to time phase 5 aredetermined by performing the color conversion processing in the waysimilar to the above manner. In this manner, the time phase imagegeneration unit 24 d generates the color image data of each of theparametric time phase images from time phase 1 to time phase 5.

Note that, the time phase image generation unit 24 d may generate thecolor image data of the parametric time phase images from time phase 1to time phase 5 by similarly changing luminosity instead of changingchroma. That is, color conversion processing is performed on the colorof the bottom left pixel of the parametric image in such a manner thatluminosity becomes 0%, 75%, 100%, 50% and 10%, and each color subjectedto this color conversion processing becomes the color of the bottom leftpixel of the parametric time phase images from time phase 1 to timephase 5.

In addition, the time phase image generation unit 24 d may generate thecolor image data of the parametric time phase images from time phase 1to time phase 5 by similarly changing transmittance instead of changingchroma.

As just described, examples in which the color image data of therespective parametric time phase images from time phase 1 to time phase5 are generated by performing the color conversion processing so as tochange one of chroma, luminosity and transmittance in accordance withthe normalized pixel values of the pixel of the same position in therespective DSA images have been explained. However, embodiments of thepresent invention are not limited to such an aspect.

For example, the color image data of the respective parametric timephase images from time phase 1 to time phase 5 may be generated on thebasis of the parametric image (color map) whose parameter is theaforementioned AUC obtained from the time variation of pixel values ofthe same position in the plurality of the sequential DSA images, in theway similar to the above manner.

Alternatively, the color image data of the respective parametric timephase images from time phase 1 to time phase 5 may be generated on thebasis of the parametric image (color map) whose parameter is theaforementioned PH obtained from the time variation of pixel values ofthe same position in the plurality of the sequential DSA images, in theway similar to the above manner.

Assuming that there are three cases of generation methods of theparametric image as to which parameter is used and there are three casesof the color conversion processing methods as to which of chroma,luminosity and transmittance is changed, at least there are at leastnine (obtained by three times three) methods of generating theparametric time phase images in the manner explained with FIG. 4.

However, as mentioned before, aside from TTP, AUC and PH, there areother parameters to be used for generating the parametric image such asthe rising inclination of the time variation curve of the concentrationof the contrast agent. In addition, the color conversion processing maybe performed in accordance with the normalized pixel value of each pixelof the same position of each DSA image in such a manner that two ofchroma, luminosity and transmittance change. Alternatively, the colorconversion processing may be performed in accordance with the normalizedpixel value of each pixel of the same position of each DSA image in sucha manner that all of the chroma, luminosity and transmittance change.

Considering these variations, there are twenty or more than twentymethods of generating the parametric time phase images in the mannerexplained in FIG. 4.

By displaying each of the parametric time phase images generated in theabove manner from time phase 1 to time phase 5 in time-series order,moving picture display can be achieved.

FIG. 5 is a schematic diagram showing the second example of the methodsof generating the parametric time phase images conducted by the timephase image generation unit 24 d in a step-by-step manner. In the waysimilar to FIG. 4, the second example will be explained by focusing onthe bottom left pixel through the five sequential DSA images shown inthe upper part of FIG. 5.

Because TTP of the bottom left pixel is 3, the bottom left pixel isdisplayed so as to become a high contrast pixel only in time phase 3 asshown in the middle part of FIG. 5. The above high contrast pixel meansa pixel displayed with raised luminosity in a parametric time phaseimage of a certain time phase.

That is, because the bottom left pixel is not the high contrast pixel inthe four parametric time phase images at time phase 1, 2, 4 and 5, thebottom left pixel is displayed with lowered luminosity in the fourparametric time phase images at time phase 1, 2, 4 and 5.

More specifically, the color of the bottom left pixel in each of theparametric time phase images at time phase 1, 2, 4 and 5 becomes a colorsubjected to the color conversion processing that gives a convertedcolor by lowering luminosity of the green color allocated in theparametric image (color map). As to how to lower luminosity, it may giveuniform luminosity (over the time phase 1, 2, 4 and 5). Alternatively,this color conversion processing may be performed so that the lower thenormalized pixel value (see the second uppermost part of FIG. 4) is, thelower the luminosity of the converted color becomes.

On the other hand, the color of the bottom left pixel of the parametrictime phase image at time phase 3 becomes a color subjected to the colorconversion processing that gives the converted color by raisingluminosity of the green color allocated in the parametric image (colormap). Thereby, the respective colors of the bottom left pixel of theparametric time phase images from time phase 1 to time phase 5 aredetermined.

As shown in the lower part of FIG. 5, the time phase image generationunit 24 d calculates colors of all the pixels of the respectiveparametric time phase images from time phase 1 to time phase 5 byperforming the same color conversion processing on the other pixels.

By displaying the parametric time phase images in time-series order sothat the high contrast pixels are brightly displayed and the rest pixelsare darkly displayed in the above manner, they are made to look likemoving picture display. That is, the sequential parametric time phaseimages, whose color shade is calculated by using TTP, become movingpicture reflecting information on arrival time of the contrast agent.

Note that, though examples in which the pixel number of each of the DSAimages, the parametric images and the parametric time phase images is 25have been explained in order to avoid complication, the pixel number ofthese images may be equal to or more than twenty-six, or equal to orless than twenty-four. In addition, as to the three sorts of imagesincluding the DSA images, the parametric images and the parametric timephase images, their pixel number in height and width does not need to beuniform.

If the pixel number of the DSA images is extremely large, the pixelnumber of each of the parametric image and the parametric time phaseimages may be thinned out so as to become a half of the pixel number ofthe DSA images in height and become a half of the pixel number of theDSA images in width, for example.

In addition, though examples of five time phases have been explained forsimplifying the explanation, the number of time phases may be six ormore.

FIG. 6 is a schematic diagram showing the judging method of abloodstream improving region after the vasodilation operation or thelike conducted by the specifying processing unit 24 e, in a stepwisefashion.

In the way similar to the aforementioned examples, consider a case wherefive pre-operative DSA images 1, 2, 3, 4 and 5 are generated from thesame imaging region of the object P before the operation, and fivepost-operative DSA images 1′, 2′, 3′, 4′ and 5′ are generated from thesame imaging region of the same object after the operation.

In this case, the parameter value acquisition unit 24 b and the colorallocation unit 24 c generate one pre-operative parametric image fromthe pre-operative DSA images 1 to 5 by using PH as a parameter in thesame manner as above (see the upper left part of FIG. 6). Similarly, theparameter value acquisition unit 24 b and the color allocation unit 24 cgenerate one post-operative parametric image from the post-operative DSAimages 1′ to 5′ by using PH as a parameter in the same manner as above(see the upper right part of FIG. 6).

Next, the specifying processing unit 24 e generates a subtraction imageby subtracting each pixel value of the pre-operative parametric imagefrom each pixel value of the post-operative parametric image, so thatthe subtraction is performed between the two pixels of the same positionbefore and after the operation.

The specifying processing unit 24 e extracts a pixel region whose pixelvalue is equal to or larger than a threshold value in this subtractionimage, as the bloodstream improving region (see the middle part of FIG.6).

Note that, the bloodstream improving region can be extracted by (a)generating the pre-operative parametric image and the post-operativeparametric image by using AUC as a parameter instead of PH and (b)performing the threshold processing on the subtraction image in the sameway as above.

Moreover, the specifying processing unit 24 e generates vessel wallemphasis image data in which contour of blood vessels (vessel walls) inthe bloodstream improving region is emphasized.

More specifically, for example, the specifying processing unit 24 e cangenerate the vessel wall emphasis image data by applying contouremphasis processing such as a Laplacian filter to the bloodstreamimproving region extracted from the above subtraction image (see thebottom part of FIG. 6).

On the other hand, the bloodstream occluded region after the vascularembolus operation or the like are similarly judged except that thesubtracted side is reversed in the generation processing of thesubtraction image. That is, the specifying processing unit 24 egenerates the subtraction image by subtracting each pixel value of thepost-operative parametric image from each pixel value of thepre-operative parametric image, and calculates the pixel region whosepixel value is equal to or higher than a threshold value as thebloodstream occluded region.

<Display Method of the Present Embodiment>

FIG. 7 is a schematic diagram showing an example of distinguishablydisplaying the bloodstream improving region by surrounding it with aframe, in moving picture display of the parametric time phase images.

As an example here, the respective parametric time phase imagescorresponding to the respective time phases of the pre-operative DSAimages are displayed in time-series order in the left side of the screenof the display unit 24 f and the respective parametric time phase imagescorresponding to the respective time phases of the post-operative DSAimages are displayed in time-series order in the right side of thescreen. The same holds true for the following FIG. 8 to FIG. 10.

As shown in FIG. 7, the display unit 24 f can distinguishably displaythe bloodstream improving region extracted by the specifying processingunit 24 e as ROI (Region of Interest) 300 surrounded with a rectangularframe, in moving picture display of both of the pre-operative parametrictime phase images and the post-operative parametric time phase images

Note that, though images up to only time phase 3 are depicted in FIG. 7in order to avoid complication, actually images on and after time phase4 are also displayed (the same holds true for the following FIG. 8 toFIG. 10).

In addition, though the pre-operative parametric time phase images aredisplayed as moving pictures for comparison, only the post-operativeparametric time phase images may be displayed so as to differentiate thebloodstream improving region (the same holds true for the following FIG.8 to FIG. 10).

In addition, though the same pixel region as the post-operativebloodstream improving region is distinguishably displayed in the movingpicture of pre-operative parametric time phase images by surrounding itwith a frame in FIG. 7, the bloodstream improving region may bedistinguishably displayed only in the post-operative moving picture likethe next FIG. 8.

FIG. 8 is a schematic diagram showing an example of distinguishablydisplaying the bloodstream improving region by blinking it, in movingpicture display of the parametric time phase images.

In the example of FIG. 8, the display unit 24 f distinguishably displaysthe bloodstream improving region as ROI 300 by blinking the bloodstreamimproving region. As to blinking display, for example, luminosity of thepixels of ROI 300 may be alternately (intermittently) raised andlowered. Alternatively, if the number of time phases is sufficientlylarge, ROI 300 may be displayed with lowered luminosity only ineven-numbered time phases like the example of FIG. 8.

FIG. 9 is a schematic diagram showing an example of a highlighted bloodvessel wall extracted by the specifying processing unit 24 e, in movingpicture display of the parametric time phase images. As shown in FIG. 9,the display unit 24 f can highlight the blood vessel wall extracted bythe specifying processing unit 24 e by using, for example, a bold linein ROI (the bloodstream improving region) 300, while distinguishablydisplaying this ROI 300 by surrounding it with a frame in each of thepost-operative parametric time phase images.

FIG. 10 is a schematic diagram showing an example of displaying only thebloodstream improving region by using the DSA images as a movinggray-scale picture and displaying the rest of the regions in color byusing the parametric time phase images, in moving picture display of theparametric time phase images.

As mentioned above, when a plurality of parametric time phase images aregenerated so as to correspond to the respective time phases of aplurality of DSA images, the display unit 24 f can perform movingpicture display of the parametric time phase images in such a mannerthat only the ROI (bloodstream improving region) 300 is substituted bythe same region of the DSA image of the same time phase.

More specifically, each pixel has pixel values of the three primarycolors including red, green and blue in the parametric time phaseimages, for example. On the other hand, each pixel of the DSA images hasonly one pixel value. This is because each pixel value of the DSA imagescorresponds to difference in X-ray transmissivity between a pixel valueof a certain time phase after administration of the contrast agent and apixel value of the mask image.

Thus, because the ROI 300 displayed by using pixel values of the DSAimages does not have data of chromatic color, it is displayed with agray-scale. However, because the rest regions are chromaticallydisplayed, the ROI 300 displayed with a gray-scale becomes adistinguishable display aspect.

Note that, though FIG. 7 to FIG. 10 are indicated by gray-scaleschematic diagrams for the sake of expedience, actually they arechromatically displayed except the ROI 300 in FIG. 10 because each ofthe parametric time phase images are formed by color image data.

In addition, though examples in which the bloodstream improving regionis distinguishably displayed have been explained in FIG. 7 to FIG. 10,the same display aspect as FIG. 7 to FIG. 10 can be applied when thebloodstream occluded region after the vascular embolus operation isdistinguishably displayed.

<Operation Explanation of the Present Embodiment>

FIG. 11 is a flow chart showing an example of the operation of the X-raydiagnostic apparatus 10 of the present embodiment, when imaging withadministration of contrast agent before and after the vasodilationoperation and display of bloodstream improving region are performed.

In the following, according to the step numbers in the flowchart shownin FIG. 11, an operation of the X-ray diagnostic apparatus 10 will bedescribed by referring to the aforementioned FIG. 1 to FIG. 10 asrequired.

[Step S1] Before the vasodilation operation, the projection data of aplurality of sequential X-ray images for the same region of the object Pare generated under known operation. More specifically, the systemcontrol unit 26 (see FIG. 1) sets all the imaging conditions of eachtime phase before and after administration of the contrast agent, on thebasis of some of the imaging conditions such as the imaging region, tubecurrent, tube voltage and a pulse width of X-rays inputted via the inputdevice 22. The high-voltage generator 44 supplies high voltage to theX-ray tube 42 in accordance with the control of the system control unit26, the X-ray tube 42 generates X-rays, and the diaphragm device 40adjusts the X-ray irradiation range to the object P.

The X-ray detector 34 detects X-rays passing through the object P,converts them into electrical signals, and inputs the electrical signalsinto the projection data generation unit 30. The projection datageneration unit 30 generates the projection data of X-ray images on thebasis of the inputted electrical signals, and stores the projection datain the projection data storage unit 28.

In this manner, the projection data of many time phases for the sameregion of the object P are generated, in such a manner that luminance ofeach pixel becomes a value in accordance with exposure dose pernon-illustrated X-ray detection element of the X-ray detector 34 beforeand after administration of the contrast agent.

Note that, though a plurality of X-ray images after administration ofthe contrast agent are necessary so as to correspond to a plurality oftime phases, the number of the X-ray image before the contrast agent maybe only one.

Moreover, the projection data generation unit 30 generates the imagedata of the plurality of sequential DSA images for the same region ofthe object P on the basis of the projection data, and stores the imagedata of these DSA images in the projection data storage unit 28.

After this, the process proceeds to Step S2.

[Step S2] The DSA image acquisition unit 24 a of the image analysisdevice 24 acquires the image data of the plurality of sequential DSAimages from the projection data storage unit 28. The parameter valueacquisition unit 24 b calculates parameter values per pixel of the sameposition from the image data of the plurality of sequential DSA images(see FIG. 2).

Note that, as to which of TTP, PH, AUC and so on is used as theparameter value, it may be selected via the input device 22 in Step S1.Alternatively, the parameter value acquisition unit 24 b mayautomatically select the parameter to be used.

Next, the color allocation unit 24 c generates the image data of oneparametric image for the plurality of sequential DSA images in themanner mentioned before (see FIG. 3).

Next, the time phase image generation unit 24 d generates the image dataof the plurality of parametric time phase images respectivelycorresponding to the plurality of (pre-operative) sequential DSA images,in the aforementioned manner. As to this generation method, the firstmethod explained with FIG. 4 and/or the second method explained withFIG. 5 may be used.

After this, the process proceeds to Step S3.

[Step S3] After the vasodilation operation, the projection data ofsequential X-ray images for the same imaging region of the same object Pas Step S1 are generated, in the way similar to Step S1. Thereby, theprojection data of many time phases are generated for the same region ofthe object P before and after the administration of the contrast agent.Moreover, the projection data generation unit 30 generates the imagedata of the plurality of sequential DSA images for the same region ofthe object P in the same way as above, and stores these image data inthe projection data storage unit 28.

After this, the process proceeds to Step S4.

[Step S4] In the way similar to Step S3, the image analysis device 24generates the image data of the plurality of parametric time phaseimages respectively corresponding to the plurality of post-operativesequential DSA images.

After this, the process proceeds to Step S5.

[Step S5] The specifying processing unit 24 e of the image analysisdevice 24 generates the subtraction image by subtracting each pixelvalue of the pre-operative parametric image from each pixel value of thepost-operative parametric image, and extracts a pixel region whose pixelvalue is equal to or higher than the threshold value in the subtractionimage, as the bloodstream improving region (see FIG. 6). In addition,the specifying processing unit 24 e generates the vessel wall emphasisimage data in which vessel walls in the bloodstream improving region isemphasized as described previously.

After this, the process proceeds to Step S6.

[Step S6] The display unit 24 f of the image analysis device 24 displaysthe post-operative parametric time phase images in time-series order, insuch a manner that the bloodstream improving region extracted in Step S5is distinguishably displayed. That is, moving picture display isperformed. At this time, the pre-operative parametric time phase imagesmay be displayed on one side of the screen and the post-operativeparametric time phase images may be displayed on the other side of thescreen for comparison like FIG. 7 to FIG. 10.

In addition, as to distinguishable display of the ROI (bloodstreamimproving region) 300, it may be surrounded by a rectangular frame likeFIG. 7, or blinking display may be performed like FIG. 8. Alternatively,blood vessel walls are emphasized in ROI 300 like FIG. 9. Alternatively,only the bloodstream improving region may be displayed as gray-scalemoving pictures by using the DSA images and the rest regions may bechromatically displayed by using the parametric time phase images likeFIG. 10.

The foregoing is the explanation of the flow of FIG. 11.

FIG. 12 is a flow chart showing an example of the operation of the X-raydiagnostic apparatus 10 of the present embodiment, when imaging withadministration of the contrast agent before and after the vascularembolus operation and display of the bloodstream occluded region areperformed. In the following, according to the step numbers in theflowchart shown in FIG. 12, an operation of the X-ray diagnosticapparatus 10 will be described by referring to the aforementioned FIG. 1to FIG. 11 as required.

[Step S11] Before vascular embolus operation, the projection data of theplurality of sequential X-ray images before and after administration ofthe contrast agent and the image data of the plurality of sequential DSAimages are generated for the same imaging region of the object P, in theway similar to Step S1 of FIG. 11.

After this, the process proceeds to Step S12.

[Step S12] The image analysis device 24 generates the image data of theparametric time phase images of the respective time phases before theoperation, in the way similar to Step S2 of FIG. 11.

After this, the process proceeds to Step S13.

[Step S13] After the vascular embolus operation, the projection data ofthe plurality of sequential X-ray images before and after administrationof the contrast agent and the image data of the plurality of sequentialDSA images are generated for the same imaging region of the same objectP as Step S11, in the same way as above.

After this, the process proceeds to Step S14.

[Step S14] The image analysis device 24 generates the image data of theparametric time phase images of the respective time phases after theoperation, in the same way as above.

After this, the process proceeds to Step S15.

[Step S15] The specifying unit 24 e generates the subtraction image bysubtracting each pixel value of the post-operative parametric image fromeach pixel value of the pre-operative parametric image, and extracts apixel region whose pixel value is equal to or higher than the thresholdvalue in the subtraction image, as the bloodstream occluded region.

After this, the process proceeds to Step S16.

Note that, the processing of emphasizing blood vessel walls is notperformed in the flow of FIG. 12 because the effect of the operation isblockage of blood flow.

[Step S16] The display unit 24 f time-sequentially displays thepost-operative parametric time phase images in such a manner that thebloodstream occluded region extracted in Step S15 is distinguishablydisplayed, in the way similar to the aforementioned FIG. 7, FIG. 8 andFIG. 10.

The foregoing is the operation explanation of the X-ray diagnosticapparatus 10 of the present embodiment.

<Effects of the Present Embodiment>

In conventional technology, one parametric image is generated beforeoperation or after operation, and the parametric image is displayed as astill picture. In still picture display, it is not necessarily easy tovisually judge a bloodstream improving region or a bloodstream improvingregion indicating the effect of the operation.

Then, in the present embodiment, the parametric time phase images of theplurality of time phases respectively corresponding to the DSA images ofthe plurality of time phases are generated from one parametric image inaccordance with time variation of pixel values.

Furthermore, because the pre-operative parametric time phase images andthe post-operative parametric time phase images are respectivelydisplayed as moving pictures, it becomes easier than the conventionaltechnology to visually judge a region with changed bloodstream amount.

Moreover, in the present embodiment, the bloodstream improving region orthe bloodstream occluded region is automatically extracted on the basisof the subtraction image between the pre-operative parametric images andthe post-operative parametric images.

This extracted bloodstream improving region or bloodstream occludedregion is distinguishably displayed in the moving picture display of theparametric time phase images in the manner of FIG. 7 to FIG. 10, forexample. Thus, a reader can easily visually judge the bloodstreamimproving region or the bloodstream improving region indicating theeffects of the operation.

By the above epoch-making and innovative technology, oversight of areader will decrease even if the difference between before and after theoperation is small.

On the other hand, in the conventional technology, there was a workburden in finding out a small difference by switching still picturedisplay of the parametric image, moving picture display of the DSAimages and still picture display of the DSA image of each time phase.However, the above work burden in the conventional technology becomesunnecessary by the present embodiment.

As a result, user-friendliness is highly improved.

<Supplementary Notes on Embodiments>

[1] In the above embodiment, an example in which the image analysisdevice 24 is disposed as one component inside the X-ray diagnosticapparatus 10 has been explained. However, embodiments of the presentinvention are not limited to such an aspect. For example, the imageanalysis device 24 may be disposed in another modality such as an X-rayCT (Computed Tomography) apparatus or a magnetic resonance imagingapparatus.

As an alternative aspect, the image analysis device 24 may function asan image analysis server connected with PACS (Picture Archiving andCommunication System). The above picture archiving and communicationsystem is a system in which image data obtained by modalities such as anX-ray diagnostic apparatus are stored in an image storage server andnecessary images are read and displayed in a reference terminal. In thiscase, the image analysis device 24 may acquire image data of theplurality of sequential DSA images for the same the object P via thepicture archiving and communication system, and display the parametrictime phase images as moving pictures in such a manner that the regionwith changed bloodstream amount is distinguishably displayed in the waysimilar to the above embodiment.

[2] In the above embodiment, examples in which the parametric time phaseimages respectively corresponding to the respective time phases of allthe acquired DSA images are generated and all the generated parametrictime phase images are displayed in time-series order have beenexplained. However, it is not necessarily essential to generate theparametric time phase images so as to respectively correspond to all thetime phases of the DSA images.

When the number of the acquired DSA images is considerably large, i.e.the time phase number of the DSA images is considerably large, the timephase number of the parametric time phase images may be thinned out to adegree at which all the generated parametric time phase images givesvisually natural moving pictures. For example, when the DSA images ofone hundred time phases are acquired, fifty parametric time phase imagesmay be generated by using the fifty DSA images of the even-numbered timephases and these fifty parametric time phase images may betime-sequentially displayed.

[3] In the above embodiment, examples in which the plurality ofsequential DSA images are generated on the basis of sequentialtwo-dimensional image data obtained by imaging before and afteradministration of the contrast agent and the plurality of parametrictime phase images respectively corresponding to these DSA images aregenerated and two-dimensionally displayed as moving pictures have beenexplained. However, embodiments of the present invention are not limitedto such an aspect.

For example, when volume data are sequentially obtained by imaging underan X-ray CT apparatus or a magnetic resonance imaging apparatus, (theparallax images of) the plurality of sequential parametric time phaseimages may be displayed as moving pictures by a naked eye stereoscopicdisplay device. In this case, the display unit 24 f is composed as anaked eye stereoscopic display device, and image data of the pluralityof the parallax images are generated per parametric time phase imagecorresponding to each imaging time.

More specifically, the sequential parametric time phase images 1 to 5are generated on the basis of the respective pixel value of the centralcross-section of volume data in the above manner, for example (asdescribed previously, frame number is not limited to five). Then, depthinformation is calculated on the basis of pixel values of all thecross-sections of the volume data, and the plurality of the parallaximages are generated for each of the parametric time phase images of theplurality of time phases on the basis of the depth information.

If the plurality of the parallax images are generated for each timephase (each imaging time), the parametric time phase images can bethree-dimensionally displayed by a naked eye stereoscopic displaydevice. As to methods of generating parallax images and structure of anaked eye stereoscopic display device, for example, conventionaltechnology described in Japanese Patent Application Laid-open (KOKAI)Publication No. 2007-94022 may be used.

[4] In the above embodiment, examples in which (a) a bloodstreamimproved region or a bloodstream occluded region due to an operation isautomatically extracted and (b) the bloodstream improving region or thebloodstream occluded region is displayed in a distinguishable aspect inmoving picture display of the parametric time phase images have beenexplained. However, embodiments of the present invention are not limitedto such an aspect.

Extraction processing of the bloodstream improving region or thebloodstream occluded region is not indispensable, and the parametrictime phase images may be simply displayed as moving pictures.

As to moving picture display, for example, the parametric time phaseimages may be displayed with the DSA images of the respective timephase.

More specifically, for example, the DSA images may be sequentiallydisplayed on the right side of the screen of the display unit 24 f, andthe parametric time phase image corresponding to the time phase of theDSA image currently displayed on the right side of the screen may bedisplayed on the left side of the screen so as to follow the display onthe right side of the screen.

As to moving picture display of the parametric time phase images on theleft side of the screen, it is preferable to distinguishably display thebloodstream improving region or the bloodstream occluded regionextracted based on the difference from the pre-operative image like theabove embodiment.

Alternatively, the post-operative DSA images, the parametric image andthe parametric time phase images may be concurrently displayed (in onescreen). For example, the respective post-operative DSA images may bedisplayed in time-series order on the upper part of the screen in thesame way as above, the parametric time phase images may be displayed intime-series order on the middle part of the screen in the same way asabove, and one post-operative parametric image may be displayed as astill picture on the bottom part of the screen.

[5] In the above embodiment, examples in which (a) the region withchanged bloodstream amount is specified on the basis of the subtractionbetween the pre-operative parametric image and the post-operativeparametric image (see FIG. 6) and (b) the region with changedbloodstream amount is distinguishably displayed in moving picturedisplay of the respective parametric time images before and after theoperation have been explained (see FIG. 7 to FIG. 10). However,embodiments of the present invention are not limited to such an aspect.

In terms of specifying the region with changed bloodstream amount, it isenough to perform comparison between two time points in the time axisfrom a time before staring an operation to a time after finishing theoperation.

For example, the region with changed bloodstream amount may beidentified on the basis of the subtraction between the parametric imageobtained from pre-operative sequential DSA images and the parametricimage obtained from sequential DSA images in the middle of theoperation, and the identified region with changed bloodstream amount maybe distinguishably displayed in the same way as mentioned above.

In addition, it is not indispensable to display both of thepre-operative sequential parametric time phase images and thepost-operative sequential parametric time phase images.

For example, only the pre-operative sequential parametric time phaseimages may be generated and sequentially displayed as moving pictures ifit is used for diagnosis purposes.

For example, if the region to be cured has already been identified, onlythe post-operative sequential parametric time phase images may begenerated and sequentially displayed as moving pictures in order toconfirm the effect of the operation.

[6] Correspondences between terms used in the claims and terms used inthe embodiment described above will be described. Note that thecorrespondences described below are just some of possibleinterpretations for reference and should not be construed as limitingthe present invention.

The image data of the parametric image generated by the color allocationunit 24 c are an example of the color map described in the claims.

The image data of the parametric time phase images generated by the timephase image generation unit 24 d are an example of the color image dataof time phase images described in the claims.

The subtraction image between the pre-operative parametric image and thepost-operative parametric image generated by the specifying processingunit 24 e is an example of the subtraction map described in the claims.

The bloodstream improving region and the bloodstream occluded regionextracted by the specifying processing unit 24 e are examples of theregion with changed bloodstream amount described in the claims.

The entirety of the system control unit 26, the projection data storageunit 28, the projection data generation unit 30, the X-ray detector 34,the C-arm 36, the table 38, the diaphragm device 40, the X-ray tube 42,the high-voltage generator 44, the diaphragm control structure 46, thetable moving structure 48, the C-arm control structure 50 and thedetector moving structure 54 that generates the projection data of X-rayimages and image data of the DSA images by performing X-ray imaging onthe object P is an example of the X-ray imaging unit described in theclaims.

[7] While certain embodiments have been described, these embodimentshave been presented by way of example only, and are not intended tolimit the scope of the inventions. Indeed, the novel methods and systemsdescribed herein may be embodied in a variety of other forms;furthermore, various omissions, substitutions and changes in the form ofthe methods and systems described herein may be made without departingfrom the spirit of the inventions. The accompanying claims and theirequivalents are intended to cover such forms or modifications as wouldfall within the scope and spirit of the inventions.

What is claimed is:
 1. An image analysis device, comprising: a processorconfigured to acquire image data of a plurality of sequential DSA imagesof a same object; calculate a parameter value per pixel, using timevariation of pixel values at a same region of the object among theplurality of sequential DSA images; generate a single parametric imagein which a color in accordance with the parameter value is allocated perpixel corresponding to the same region of the object; and generate aplurality of parametric time phase images from the single parametricimage and the calculated parameter value, each pixel of each of theplurality of parametric time phase images having a color converted fromthe color of a corresponding pixel of the single parametric image, byusing the calculated parameter value.
 2. The image analysis deviceaccording to claim 1, wherein the processor is further configured togenerate the plurality of parametric time phase images in such a mannerthat at least one of luminosity, chroma, and transmittance of each pixelchanges between the plurality of parametric time phase images.
 3. Theimage analysis device according to claim 2, further comprising a displayconfigured to display the plurality of parametric time phase images as acolor moving image.
 4. The image analysis device according to claim 3,wherein the processor is further configured to specify a region with achanged bloodstream amount based on a subtraction image between theplurality of parametric time phase images.
 5. The image analysis deviceaccording to claim 4, wherein the processor is further configured toacquire the plurality of sequential DSA images, which are imaged beforeand after an operation; and calculate a subtraction map between thesingle parametric image generated based on the DSA images imaged beforethe operation and the single parametric image generated based on the DSAimages imaged after the operation, and to specify the region with thechanged bloodstream amount by performing threshold processing on eachpixel of the subtraction map.
 6. The image analysis device according toclaim 4, wherein the display is configured to distinguishably displaythe region with the changed bloodstream amount by surrounding the regionwith the changed bloodstream amount with a frame, in display of theplurality of parametric time phase images.
 7. The image analysis deviceaccording to claim 4, wherein the processor is further configured togenerate vessel wall emphasis image data in which a vessel wall in theregion with the changed bloodstream amount is emphasized; and thedisplay is configured to distinguishably display the vessel wall basedon the vessel wall emphasis image data, in display of the plurality ofparametric time phase images.
 8. The image analysis device according toclaim 1, wherein the processor is further configured to generate theplurality of parametric time phase images so as to respectivelycorrespond to the sequential DSA images, by performing color conversionin such a manner that at least one of luminosity, chroma, andtransmittance of each pixel changes between the plurality of parametrictime phase images.
 9. The image analysis device according to claim 1,wherein the processor is further configured to specify a region with achanged bloodstream amount based on a subtraction image between theplurality of parametric time phase images; and the image analysis devicefurther includes a display configured to display the plurality ofparametric time phase images as a color moving image.
 10. The imageanalysis device according to claim 9, wherein the display is configuredto distinguishably display the region with the changed bloodstreamamount by surrounding the region with the changed bloodstream amountwith a frame, in display of the plurality of parametric time phaseimages.
 11. The image analysis device according to claim 9, wherein thedisplay is configured to distinguishably display the region with thechanged bloodstream amount by blinking the region with the changedbloodstream amount, in display of the plurality of parametric time phaseimages.
 12. The image analysis device according to claim 9, wherein thedisplay is configured to distinguishably display the region with thechanged bloodstream amount by displaying only the region with thechanged bloodstream amount with gray-scale and displaying all otherregions in color, in display of the plurality of parametric time phaseimages.
 13. The image analysis device according to claim 9, wherein theprocessor is further configured to generate vessel wall emphasis imagedata in which a vessel wall in the region with the changed bloodstreamamount is emphasized; and the display is further configured todistinguishably display the vessel wall based on the vessel wallemphasis image data, in display of the plurality of parametric timephase images.
 14. An X-ray diagnostic apparatus, comprising: X-rayimaging circuitry configured to generate projection data of X-ray imagesby detecting X-rays passing through an object before and afteradministration of a contrast agent, and to generate image data of aplurality of sequential DSA images of the object based on eachsubtraction between an X-ray image before administration of the contrastagent and each of sequential X-ray images obtained after administrationof the contrast agent; and the image analysis device according to claim1 configured to calculate the parameter value per pixel, using the timevariation of the pixel values of the respective sequential DSA images,to generate the single parametric image in which the color in accordancewith the parameter value is allocated per pixel, and to generate theplurality of the parametric time phase images from the single parametricimage and the calculated parameter value, each pixel of each of theplurality of the parametric time phase images having a color convertedfrom the color of a corresponding pixel of the single parametric image,by using the calculated parameter value.